Social-welfare-maximizing mechanism design: There is large literature on mechanism design where agents have private information. The VCG mechanism, presented in the seminal paper of [1]}, is the only truthful dominant mechanisms that maximizes the utilitarian social welfare under certain assumptions, including unrestricted preferences and at least three different outcomes [2]}. VCG mechanisms are also ex-post individually rational under monotonicity of the choice set and non-negativity of externalities. However, VCG mechanisms have major practical shortcomings. In particular, they are not individually rational and budget balanced at the same time.
